Temperature and microstructure dependence of localized tensile deformation of superelastic NiTi wires

0517457 - FZÚ 2020 RIV GB eng J - Článek v odborném periodiku
Chen, Y. - Tyc, Ondřej - Kadeřávek, Lukáš - Molnárová, Orsolya - Heller, Luděk - Šittner, Petr
Temperature and microstructure dependence of localized tensile deformation of superelastic NiTi wires.
Materials and Design. Roč. 174, July (2019), s. 1-21, č. článku 107797. ISSN 0264-1275. E-ISSN 1873-4197
Grant CEP: GA MŠMT(CZ) EF16_019/0000760; GA MŠMT(CZ) LM2015088; GA ČR GA16-20264S; GA ČR GA18-03834S
Grant ostatní: OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760
Institucionální podpora: RVO:68378271
Klíčová slova: heat-treatment * memory * strain * NiTi wire * localized tensile deformation * martensitic transformation * superelasticity * strain recoverability
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 6.289, rok: 2019
Způsob publikování: Open access

Superelastic NiTi wires possessing wide range of microstructures were deformed in tensile tests up to the end of the stress plateau in a wide temperature range20200 degrees C. unloaded and stress free heated to similar to 200 degrees C. The recoverability of upper plateau strains was evaluated in dependence on the test temperature and wire microstructure. At low temperatures below 20 degrees C, the upper plateau strains are fully recoverable upon unloading and heating. With increasing test temperature, however, the recoverability of upper plateau strains becomes gradually lost. Unusually long upper plateaus (10-17%) were observed at test temperatures, at which the upper plateau stress approached the yield stress for plastic deformation of martensite. The volume fraction of the martensite phase at the end of the stress plateau (evaluated by in-situ electric resistance and synchrotron x-ray diffraction) decreases with increasing test temperature in the range where the long plateaus were observed. TEM analysis revealed high density of {114) austenite twins in wires deformed in this temperature range. These observations are rationalized by gradual increase of the activity of the stress-induced B2> B19' B2(T) martensitic transformation into twinned austenite and plastic deformation by dislocation slip with increasing test temperature. (C) 2019 The Authors. Published by Elsevier Ltd.
Trvalý link: http://hdl.handle.net/11104/0302763